Detailed data on public expenditure on education, in comparison to the total expenditure of the government and India's GDP is available at the Education Ministry's web site. Analysing the data by looking at it in graphical form, throws up some interesting points.
Figure 1: Public expenditure on education as a percentage of GDP (blue) and as a percentage of expenditure on all sectors together.
Figure 2: Public expenditure on education (green), on all sectors (blue) and India's GDP (red).
Note: All figures above are in crores of rupees. A crore equals 10,000,000 (ten million)
The government's education expenditure as a percentage of GDP (blue line in Figure 1) has never ever risen above 4.3% of GDP, despite the target of 6% having been set as far back as 1968 by the Kothari Commission. Looking at Figure 2 above, the GDP (red line) seems to be rising at a much much faster pace than the government's education expenditure (green line) to be able to reach the 6% target. Finding the money to bridge this gap will be quite a challenge. Though the 6% target finds mention in the manifestos of all parties, I've not seen any mention in any of the manifestos on how they plan to raise the funds to be able to meet this target.
Using 2001-02 figures, public expenditure on education was Rs. 84,179 Crores (at 4.02% of GDP). So to have achieved the 6% target, we would have had to spend Rs. 125,641 crores, an additional Rs. 41,461 crores over what was spent, about a 50% increase. The GDP has been growing much faster over the past 2 years than before, so it will be so much harder to achieve the 6% target.
But the public expenditure on education as a percentage of government expenditure across all sectors (red line in Figure 1 above) has been as high as 14.6% and averages 13.5% over the past few years. (It would be interesting to find out what fraction of government expenditure across all sectors goes towards interest payments, salaries and pensions, defence and other major expenditure heads, to put the education spending in perspective.)